The invention generally relates to electrospray aerosol generators.
A prior art charge-neutralized electrospray aerosol generator is disclosed by Kaufman et al., in U.S. Pat. No. 5,247,842 and is manufactured by TSI, Inc. as, by way of example, Electrospray Aerosol Generator Model 3480. This device generates small, highly charged liquid droplets and accelerates them through a small orifice into a neutralization chamber where their high charge states are reduced by a radioactive (bipolar) neutralizer. The liquid droplets contain dissolved materials or suspended solid particles. As soon as the droplets are generated they begin drying such that when they enter the neutralization chamber they have dried to solid particles.
The charge fraction of particles after passing through the neutralization chamber is determined by the size of the final dried particles, hence the smaller the particle is, the lower the charged fraction. Since the charged particles are used for subsequent analysis, achieving higher charge fractions or allowing a higher proportion of droplets generated by the electrospray device to be neutralized before they are lost would be advantageous.